Physicists may have found evidence of dark matter

By Eric Berger

April 3, 2013Updated: April 3, 2013 10:08pm

Photo: Anonymous, HOPD

This image shows an artist's concept of the Alpha Magnetic Spectrometer, a rounded module installed on the International Space Station launched in 2011. The AMS has been searching for evidence of dark matter, which has never been directly observed. CERN, the European Organization for Nuclear Research, released the first results of the experiment on Wednesday.

This image shows an artist's concept of the Alpha Magnetic...

A $2-billion probe designed to sniff the universe for cosmic rays and other exotic particles, including evidence of dark matter, has done just that, scientists said Wednesday.

The first data collected by the Alpha Magnetic Spectrometer, launched aboard a space shuttle to the International Space Station in 2011, found an excess of particles known as positrons streaming through the cosmos.

Such positrons - the positively charged counterparts of electrons - are antimatter and could be coming from one of several sources.

"This remarkable excess of positrons puts a very strong smell in the scientific nose that there is a new field of nature at work here," said Peter McIntyre, a Texas A&M University physicist who helped develop the instrument.

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Most tantalizing is the possibility that the positrons result from the collision of dark matter. Scientists believe this mysterious form of matter makes up about 27 percent of the mass of the universe, but they have never directly observed it.

"Over the coming months, AMS will be able to tell us conclusively whether these positrons are a signal for dark matter, or whether they have some other origin," said Samuel Ting, a Nobel Prize winning Massachusetts Institute of Technology physicist who is leading the experiment.

During news conferences on Wednesday, Ting took pains to thank NASA for both launching the 7.5-ton probe into space and housing it aboard the space station, which provides power.

The instrument, built over the course of 17 years, almost never flew.

As recently as a few years ago, NASA administrator Michael Griffin removed the AMS from the shuttle launch schedule because it did not have the funds for an additional flight and was unwilling to potentially risk the loss of a space shuttle crew.

After intense pressure from Congress, which in turn kept hearing about the significance of the AMS, the mission made it back onto the launch schedule after Charlie Bolden became NASA administrator in 2009.

Validation

The initial success of the AMS, which scientists say could operate for up to 20 years, helps to validate the space station as a laboratory for conducting research in space.

"This is what the space station was born for," said Mark Sistilli, NASA's program manager for the AMS.

Some local scientists agreed.

"This was really impressive data," said Paul Padley, a physicist at Rice University. "It is a very beautiful result and I think the best thing being done with the space station."